TY - CONF ID - deploy105 UR - http://deploy-eprints.ecs.soton.ac.uk/105/ A1 - Iliasov, Alexei A1 - Dotti, Fernando A1 - Romanovsky, Alexander Y1 - 2009/09// N2 - The two dependability means considered in this paper are rigorous design and fault tolerance. It can be complex to rigorously design some classes of systems, including fault tolerant ones, therefore appropriate abstractions are needed to better support system modelling and analysis. The abstraction proposed in this paper for this purpose is the notion of operation mode. Modes are formalised and their relation to a state-based formalism in a refinement approach is established. The use of modes for fault tolerant systems is then discussed and a case study presented. Using modes in state-based modelling allows us to improve system structuring, the elicitation of system assumptions and expected functionality, as well as requirement traceability. PB - IEEE CS Press TI - Structuring Specifications with Modes M2 - Brazil AV - public T2 - Fourth Latin-American Symposium on Dependable Computing (LADC) ER -